Neutrino Effects in Nucleosynthesis

It is a great pleasure to attend this meeting in honor of a long-time friend, Frank Avignone, and dedicated to his favorite subject, neutrino physics. In contrast to the rare neutrino events that Frank has measured in the laboratory, I will talk about an environment where neutrino reactions are so frequent that they determine much of the chemistry of the matter. That environment is the progenitor star’s envelope in the first seconds after a core-collapse supernova. Here the neutrinos directly synthesize new nuclei, and help to eject that matter into the interstellar medium, where it is incorporated into stars like our sun. The neutrinos also control the isospin of the nucleon soup that is the likely site of the r-process. It follows that there is an intimate connection between the properties of neutrinos, including phenomena like neutrino oscillations, and supernova nucleosynthesis.